This application relates to battery charging systems and, in particular, to systems for charging, and maintaining the charge level of, lead-acid batteries, particularly thin-film lead acid batteries of the type manufactured by Johnson Controls, Inc., under the designation xe2x80x9cInspira,xe2x80x9d or by Bolder Technologies, under the designation xe2x80x9cBolder 9/5 sub-C T.F.xe2x80x9d (Thin Metal Film).
Certain kinds of lead-acid batteries, such as thin-film lead-acid batteries, must be carefully maintained in order to avoid degradation. Thus, fully-charged batteries of this type must have their charge maintained by a trickle charging system when the battery is not in use, otherwise the battery could become inoperable after about of month of non-use. Furthermore, after the battery has been discharged in use, it must be recharged promptly to avoid degradation. Waiting to recharge could result in serious deterioration and, if left too long, the damage could become irreversible.
Batteries which have been degraded through improper maintenance may be difficult to recharge after use. Thus, while they may reach a specified voltage during charge, they may be unable to maintain a suitable voltage under load.
This application describes an improved battery charging system which avoids the disadvantages of prior systems, while affording additional structural and operating advantages.
An important aspect is the provision of a battery charging system which can improve the performance of lead-acid batteries which have become degraded through improper maintenance.
Another aspect is the provision of a charging system of the type set forth, which can maintain the condition of lead-acid batteries.
Another aspect is the provision of a battery charging system of the type set forth which is of relatively simple and economical construction.
Still another aspect is the provision of a battery charging system of the type set forth which is automatically controllable.
Certain ones of these and other aspects maybe attained by providing a charge maintenance system for a lead-acid battery comprising: a charger circuit adapted to be coupled to the battery for rapid charging thereof, a load and a switching device adapted to be connected in series across the battery, a voltage monitor circuit adapted to be coupled to the battery for monitoring the terminal voltage thereof, and a processor coupled to the charger circuit and to the switching device and to the monitor circuit and responsive to battery terminal voltage for controlling operation of the charger circuit and the switching device, the processor operating under stored program control for subjecting the battery to alternate loading and charging cycles until a predetermined battery voltage criterion is met.